The present invention relates to a method of doing a broadcast service of a short message in a communication system. Generally, in the service of a mobile communication system like CDMA, the broadcast message service provided to the subscribers is provided to the mobile terminal (or a mobile station) of said subscribers through paging channels and traffic channels. This broadcast message does not request the subscribers to answer whether or not the terminal receives the transmitted broadcast message because of its essential peculiarities.
Three methods exist for transmitting the broadcast message by said paging channels. First, a multi-slot broadcast transmission method sends the broadcast message to all slots of a control channel to send the broadcast message by using all the mobile terminals that are located in the service area of a base station. This is the simple and fast method having no time delay in the message. However, this method gives a large load to the control channel and makes the process of the other message impossible. The second is a multi-slot broadcast paging method. This is a method improved from the multi-slot broadcast transmission method. This method informs all the terminals of the broadcast by transmitting the general paging messages of small size instead of large to all slots of the control channel and then transmits the broadcast message. The third is a periodic broadcast paging method. This is the most effective method. This method informs the terminals of periodically transmitting the broadcast message from the base station.
After then, when a predetermined period is passed, the periodic broadcast paging method transmits the broadcast message. The first slot of the period of which all the terminals are informed is called a reference slot. During this slot, a general page message including the broadcast address to be transmitted in future is transmitted. Through this broadcast address information, the terminals recognize the type and arrival time of the message and decide whether the terminals receive the message. The broadcast message corresponding to each broadcast address is transmitted by the period of three slots following the reference slot. The terminal (or the mobile station) which receives the broadcast messages by the method as described above displays the messages on its display device. The conventional techniques are the arts based on the International Standardization IS-637 concerned with the short message and uses IS-95 for the radio communication of the message transmission between a base station and its terminals.
FIG. 1 is a block diagram showing the network configuration of a general CDMA system for the broadcast service of the short message.
In FIG. 1, the base station (BS) includes the base transceiver subsystem and the base station controller. Referring to FIG. 1, the mobile communication service basically using the CDMA system provides radio or wireline communication to the mobile communication subscribers by using the public switch telephone network(PSTN) 1 for the general telephone subscribers, which is provided by the communication network agent, and the integrated service digital network(ISDN) 2 providing communication service for both voice and data by a digital subscriber line.
A mobile switching center (MSC) 3a performs a circuit switching and a transit paging processing so that the subscriber can communicate with other mobile subscribers or general wireline subscribers by the mobile communication service and performs the functions of hand-off and roaming to provide a good quality of a communication service, and takes charge of the transport layer for the broadcast message transmission (20 in FIGS. 2 and 3).
Furthermore, the base transceiver subsystem 3b is connected with the mobile station 4, which is either in a geostationary position or in moving, by the radio communication path. Therefrom, the base transceiver subsystem 3b also connects the mobile station 4 with the device in the base station controller by radio or wireline path and takes charge of the relay layer 30 in FIGS. 3 and 4 for the broadcast message transmission.
Furthermore, the base transceiver subsystem contains the information about various kinds of mobile communication connected with the mobile switching center. Therefore, the base transceiver subsystem also contains the current position information of the mobile station 4, the state of the mobile communication subscribers, the statistical data about the mobile communication and the information concerning to various services. Both the home location register 6 to be connected with radio/wireline subscribers and the visitor location register 5 to be connected with the mobile switching center 3a in order to search the information for processing the paging from other network subscribers are included in the base transceiver subsystem 3b.
A cell broadcast center 7 which is an important element in the broadcast message transmission takes charge of the teleservice layer (10 in FIGS. 3 and 4). The short message entity (8) provides the broadcast message to said cell broadcast center 7.
The mobile communication service process of the basic network of the CDMA system in FIG. 1 is omitted and only the service for the broadcast message will be explained here.
Referring to FIG. 1, a communication network agent selects one of the three broadcast message transmission methods by the paging channels previously described.
A short message entity 8 sends the broadcast message that will be transmitted to the cell broadcast center 7 which takes charge of the teleservice layer 10. The cell broadcast center 7 sends the broadcast message to the mobile station 4 through the mobile switching center 3a which takes charge of the transport layer 20 and through the base transceiver subsystem 3b which takes charge of the relay layer 30 shown in FIGS. 2 and 3.
Said base transceiver subsystem 3b makes said broadcast message included in the data burst message and transmits it to the mobile station 4 through the paging channel by said selected broadcast message transmission method.
The multi-slot broadcast transmission method uses the data burst message. The remaining two methods, the multi-slot broadcast paging method and the periodic broadcast paging method, use a general paging message with the data burst message.
The address field in the data burst message or the general paging message is filled with the broadcast address that is the address not the inborn address of the mobile station 4 but for the broadcast message transmission. According to this broadcast address, whether or not the broadcast message is received is decided.
FIG. 2 shows the broadcast address for the broadcast message transmission in a conventional system. This address consists of two priority bits (PRIORITY), six message identification bits (MESSAGE_ID), eight zone identification bits (ZONE_ID), sixteen service bits (SERVICE) and eight language bits (LANGUAGE).
The broadcast address will be explained as follows. The two priority bits (PRIORITY) are to decide the priority of the broadcast messages to be broadcast when a plurality of broadcast messages are transmitted.
The six message identification bits (MESSAGE_ID) are to decide whether the current broadcast message is a duplicate copy of the message that has already been transmitted in order to avoid a duplicate transmission.
The eight zone bits (ZONE_ID) are to discriminate an identical message received from a plurality of zones different from each other.
The sixteen service bits (SERVICE) are used to classify the broadcast message transmission services by their items. The eight language bits (LANGUAGE) are used as language indicator bits for the classification of the languages used for the broadcast message.
FIG. 3 shows the protocol stack structure for the broadcast message transmission service.
The link layer 40 in the lowest level is a protocol layer for establishing the connection of a communication circuit for the communication service.
Relay layer 30 of which the base transceiver subsystem 3b of FIG. 1 takes charge is a protocol layer to discard, when broadcast messages having an identical broadcast address are received overlapping in time within a broadcast period, the overlapping message. Relay layer 30 also takes charge of the communication path allocation, the address establishment and release.
Transport layer 20 of which the mobile switching center 3a takes charge is a protocol layer for the broadcast message transmission between the cell broadcast center 7 and the base transceiver subsystem 3b and takes charge of the paging connection management, data classification and data flow control.
Teleservice layer 10 of which the cell broadcast center 7 takes charge is a protocol layer to provide the broadcast message transmission service by broadcast message subparameters.
The transmission of the broadcast message provided by the broadcast message subparameters of the teleservice layer 10 is achieved by the parameters provided from the transport layer 20), the relay layer 30 and the link layer 40 which are the protocol layers lower than the teleservice layer 10.
FIG. 4 shows the broadcast message subparameters of said teleservice layer 10. All the subparameters may be used optionally. Generally the subparameters of the broadcast message include a message identifier, a user data, a message center type stamp, a validity period-absolute, a validity period-relative, a priority indicator, an alert on message delivery, and a language indicator.
FIG. 5 shows the primitive type of relay layer 30 and the transport layer 20 in the structure of the protocol stack shown in FIG. 2.
There are four steps in the primitive between said two layers that are a request step requesting the processing of arbitrary work, an indication step informing of said requested work, a response step responding to said informed work, and a confirm step confirming the response to the request.
The relationship between the relay layer 30 and the transport layer 20 by the primitive is explained as follows.
After the request step requesting the broadcast message transmission in the transport layer 20, said relay layer 30 sends an indication for informing of the broadcast message transmission to the transport layer 20. At this time, the transport layer 20 responds so as to decide whether allowing the broadcast message transmission.
To the response, the transport layer 20 performs said broadcast message transmission by the confirm step of the relay layer 30.
According to the conventional arts described beforehand, the contents, for example a telephone number, corresponding to the received broadcast message is simply displayed on the display device of the terminal. Furthermore, in the case that the subscriber who receives the broadcast message is interested in the information of the received broadcast message, the subscriber must first store the displayed number. Therefore, if the subscriber inputs the number, the subscriber is automatically connected to the broadcast message provider and can confirm the information.
As described beforehand, according to the conventional technique, the information of the received broadcast message is only displayed on the LCD display of the terminal. Therefore, the following problems are presented.
First, for the case that the sender location of the received broadcast message is required to be stored in an address directory in the terminal in order to be used in the future, the displayed sender location must be memorized. Then, the user must store the memorized sender location in the address directory by using a separate process of the terminal.
Second, if the user wants to confirm the information of the received broadcast message, the user must memorize the previously displayed telephone number. Then, the user has to input the memorized telephone number by the keypad and make the connection with the information provider of the broadcast message. Therefore, memorizing and dialing the previously displayed telephone number must be vexatious processes.
Third, because of the above two inconvenient processes, the quality and efficiency of the broadcast service of the originally planned short message can decrease.